David Courard-Hauri, Ashley A. Wick, Lindsey K. Kneubuhler, and Keith S. Summerville.
Abstract: An understanding of the movement dynamics of invertebrates can be critical to their conservation, especially when managing relatively small, isolated habitats. However, for many species little is known about movement patterns and behavior on the scale of one or several habitat patches within a single management unit or nature preserve, possibly complicating conservation decisions when passive recolonization following disturbance such as burning is unlikely. In this work we use individual mark and recapture (IMR) methods to follow the movements of two species of grassland butterfly (Megisto cymela Drury and Speyeria cybele F.) within a 240 hectare forest and grassland preserve in central Iowa, USA. Analysis of intra-seasonal movement was performed using a Markovian technique and Monte Carlo estimation. Significant redistribution was seen in both species, with 55.7% of S. cybele and 31.1% of M. cymela undergoing interpatch movement. Median movement rates during the study were 114 m/day for S. cybele and 38 m/day for M. cymela, with the top decile moving at a rate of over five times these values. This movement did not appear to be random. S. cybele exhibited directed movement towards patches with high nectaring potential, although not all such patches were selected. M. cymela aggregated in particular prairie patches, especially those with high edge to area ratios, although the reason for aggregation is not clear. This patch-scale movement observed in both species may have important management implications, especially if replicated in species of conservation concern.